X linked mental retardation: a family with a separate syndrome?

Intellectual disability and overgrowth-A new case of 19p13.13 microdeletion syndrome with digital abnormalities

19p13.13 microdeletion has been consistently associated with intellectual disability, overgrowth, and macrocephaly. We report a 19p13.13 microdeletion, detected by array CGH, in a girl with moderate intellectual disability, overgrowth with macrocephaly, prominent digit pads and deep digital creases, hypotonia, ataxia, and strabismus. This clinical report helps to delineate the role of some of the deleted genes, as well as the phenotype of recently described 19p13.13 microdeletion syndrome, including the description of novel digital abnormalities.

A microdeletion syndrome due to a 3-Mb deletion on 19q13.2--Diamond-Blackfan anemia associated with macrocephaly, hypotonia, and psychomotor retardation

We report on a boy with congenital pure red blood cell aplasia [Diamond Blackfan anemia (DBA)] and severe congenital hypotonia, macrocephaly, hypertelorism, a broad and tall forehead, medial epicanthus, and facial hypotonia with mouth-breathing and drooling, an affable and out-going personality, and a general psychomotor retardation. These features show similarity to the phenotype of the X-linked FG syndrome. DBA was diagnosed at the age of 4 months, and the boy underwent treatment with transfusion and with prednisolone. He had a normal 46, XY karyotype, but fluorescence in situ hybridization (FISH) analysis to metaphase chromosomes revealed a 3-Mb deletion on 19q13.2. This chromosomal region has previously been linked to the DBA phenotype and one 19q13 microdeletion has been identified in a patient with DBA. This deletion coincides with the deletion reported here. We suggest that the complex phenotype of our patient, including both DBA and the associated features, represent a microdeletion syndrome.

Fragile X mutation and FG syndrome-like phenotype

We present data on 4 mentally retarded brothers, 2 of whom were dizygotic twins with congenital hypotonia, constipation, head size disproportionately large for length or height, and a combination of minor anomalies suggestive of FG syndrome. These brothers have a mentally retarded full sister with similar minor anomalies and an older half-brother with the Martin-Bell syndrome. The mother is mentally retarded; 4 of 7 individuals are positive for fragile X, but all have a CGG expansion ranging from 0.2-2 to 4 kb. Although the phenotype is not completely typical of the FG syndrome and the coincidence of the FMR1 mutation and segregation of the MCA/MR phenotype are highly unlikely, the FMR1 mutation may affect morphogenesis more extensively and differently than the Martin-Bell syndrome does to effect an FG syndromelike phenotype in certain families. This phenotype does not appear to be a contiguous gene syndrome, but an effect of the FMR1 mutation on an adjacent gene must be considered.

Fragile X family with unusual digital and facial abnormalities, cleft lip and palate, and epilepsy

We present a fragile X family with unusual clinical manifestations. These findings, which often occur in the X-linked FG syndrome, include minor limb anomalies, cleft lip and palate, characteristic facial appearance, gastrointestinal problems and epilepsy, and intellectual disability. In a total sample of 54 fra(X) families, the frequency of minor limb anomalies was estimated to be 32% in the affected males and 19% in the female heterozygotes. These anomalies tend to occur in several members of the same family, where some craniofacial abnormalities reported as characteristic of the FG syndrome have also been encountered. Possible mechanisms for the occurrence of these unusual manifestations in the fra(X) families are discussed.